title: Phylogenetic influences on leaf trait integration in Pelargonium (Geraniaceae): convergence, divergence, and historical adaptation to a rapidly changing climate.
abstract: OBJECTIVE
  Trait integration may improve prediction of species and lineage responses to future climate change more than individual traits alone, particularly when analyses incorporate effects of phylogenetic relationships. The South African genus Pelargonium contains divergent major clades that have radiated along the same seasonal aridity gradient, presenting the opportunity to ask whether patterns of evolution in mean leaf trait values are achieved through the same set of coordinated changes among traits in each clade.
  
  
  METHODS
  Seven leaf traits were measured on field-collected leaves from one-third of the species (98) of the genus. Trait relationships were examined using phylogenetic regression within major clades. Disparity analysis determined whether the course of trait evolution paralleled historical climate change events.
  
  
  RESULTS
  Divergence in mean trait values between sister clades A1 and A2 was consistent with expectations for leaves differing in longevity, despite strong similarity between clades in trait interactions. No traits in either clade exhibited significant relationships with multivariate climate axes, with one exception. Species in clades C and A2 included in this study occupied similar environments. These clades had similar values of individual trait means, except for δ(13)C, but they exhibited distinctive patterns of trait integration.
  
  
  CONCLUSIONS
  Differing present-day patterns of trait integration are consistent with interpretations of adaptive responses to the prevailing climate at the time of each clade's origin. These differing patterns of integration are likely to exert strong effects on clade-level responses to future climate change in the winter rainfall region of South Africa.
authors.affiliation: Department of Ecology and Evolutionary Biology, Unit-3043, 75 North Eagleville Road, University of Connecticut, Storrs, Connecticut 06269-3043 USA. Cynthia.s.jones@uconn.edu
authors.forename: Cynthia S
authors.initials: CS
authors.lastname: Jones
authors.forename: Hugo I
authors.initials: HI
authors.lastname: Martínez-Cabrera
authors.forename: Adrienne B
authors.initials: AB
authors.lastname: Nicotra
authors.forename: Kerri
authors.initials: K
authors.lastname: Mocko
authors.forename: Elizabeth M
authors.initials: EM
authors.lastname: Marais
authors.forename: Carl D
authors.initials: CD
authors.lastname: Schlichting
mesh_terms: D000222:Adaptation, Physiological / Q000235:genetics*; D005075:Biological Evolution; D018506:Gene Expression Regulation, Plant; D031316:Pelargonium / Q000033:anatomy & histology* / Q000235:genetics* / Q000502:physiology; D011891:Rain; D012621:Seasons; D013019:South Africa; D013997:Time Factors
keywords: Cape Floristic Region; Geraniaceae; Greater Cape Floristic Region; Pelargonium; climate; functional traits; leaves; phylogenetic regression; trait integration